Anionic surfactants are mixed with other surfactants or builders to be used in medical emulsifiers, cosmetic emulsifiers, and detergents including laundry detergents, kitchen detergents, and foaming agents for toothpaste.
As a method for producing an anionic surfactant powder or granule having relatively high purity, those methods have been conventionally known, including a method of spraying an anionic surfactant solution into a fluidized bed dryer to dry (U.S. Pat. No. 6,455,488), a method of drying with a rotary film evaporator to decrease a moisture content to less than 1% by weight (JP-A 11-5999), and a method of removing at least a part of solvent by irradiating a microwave (JP-A 2002-129197).
As a method for producing an anionic surfactant powder or granule, those methods have been known, including a method of spraying an aqueous slurry of alkylsulfate to dry (JP-A 54-106428), a method of forming a thin film of concentrated slurry on the inner surface of a heating wall, concentrating and drying the slurry (JP-A 2-222498, JP-A 5-331496), and a method of adding an anionic surfactant paste to a powdery raw material at a reduced pressure and simultaneously conducting drying and granulation (JP-A 2005-68413).
As a prevention against sticking of a detergent composition in production thereof by granulation, those methods have been known, including a method of adding an antisticking agent (JP-A 7-133498), a method of applying an impact force to a granulator (JP-A 2001-246238), a method of regulating a Froude number and an adding rate of a liquid raw material (JP-A 2006-143998).